Container wall post-forming

ABSTRACT

Tube containers that have a barrier structure can be altered in shape by post-forming techniques. This post-forming comprises placing a formed and heated tube on a mandrel and having a surrounding mold having the final desired shape of the tube. The inner wall then is pressurized through the mandrel with an optional use of a vacuum on the mold. The tube walls are altered in shape to a degree that will not be deleterious to the barrier properties of the tube wall.

FIELD OF THE INVENTION

This invention relates to a finished container where the shape of atleast part of the structure of the walls is changed. More particularly,this invention relates to a tube container where the shape of the tubecontainer is changed after the formation of the tube.

BACKGROUND OF THE INVENTION

In most instances the container is given its final shape at the timethat it is manufactured. However, in some instances the container shapeis modified after the container is made. This is to provide thecontainer with some utilitarian feature or to provide a decoration. Ithas been found that a post forming technique is very useful for addingfeatures or decoration to tube containers.

Japanese Patent Publication 56-20970 discloses a technique for modifyingthe shape of tube containers by means of placing the tube on a heatedmandrel and blowing the tube wall to the shape of a surround mold. Thismodifies the tube wall. The heated mandrel is removed, the mold openedand the tube with an altered surface removed. U.S. Pat. No. 5,756,038discloses a modification of this process where the mandrel has recessesand a vacuum is shown on the mandrel and/or is blown from thesurrounding mold. The tube wall takes the shape of the mandrel recesses.The tube then is stripped from the mandrel recesses. These areinteresting processes for making post-formed tubes. However, neitherprocess takes into account tube walls that have a barrier layer. Such abarrier layer is part of a laminate or injection blowmolded tube. Insituations where the barrier layer is for organic substances such asflavors or fragrances, it will be a metal layer, such as an aluminumlayer or an organic layer, such as an ethylene vinylalcohol (EVOH)layer. In the alteration of the shape of a tube wall it is importantthat the barrier layer of the tube wall not be breached.

BRIEF SUMMARY OF THE INVENTION

The invention is directed to the post-forming of containers, such astube containers, where the container structure contains a barrier layerfor moisture and/or organics. Organic barriers are usually directed topreclude the passing of flavors and fragrances through a container wall.These barriers are foils that are a part of a multilayer container walland can be either organic or inorganic foils, such as aluminum orethylene vinylalcohol foils. However, in the post-forming this barrierfoil layer cannot be breached. This barrier foil layer must remaincontinuous, and continuous is a sufficiently thick layer to be aneffective barrier after any post-forming. The metal or metal alloy ofany inorganic barrier must have a sufficient ductility that the metalcan spread and thin without any breaches. Likewise, for an organicbarrier it must be able to thin, yet retain a sufficient thickness toprovide an effective barrier. For a metal foil barrier layer the metalfoils can initially be about 7 microns to about 50 microns, andpreferably about 10 microns to 25 microns. This can be stretched about1% to about 25%. More highly ductile materials can be subject to agreater degree of stretching. For an organic foil it can initially beabout 5 microns to about 50 microns, and preferably about 10 microns toabout 25 microns, and can be stretched about 1% to about 100% and retaineffective barrier properties.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-section of a typical container wall having a metalfoil layer.

FIG. 2 is a cross-section of a typical container wall having an organicfoil layer.

DETAILED DESCRIPTION OF THE INVENTION

The post-forming of containers while maintaining the barrier propertiesof the container walls will now be described in more detail. FIGS. 1 and2 describe the wall of typical containers having barrier walls. Thesecontainer walls are formed from a laminate material or are formed byextrusion blowmolding. If the wall contains a metal foil it will beformed from a laminate material.

Although the present invention is applicable to any container, it isparticularly applicable to tube containers.

FIG. 1 shows a foil laminate wall of a tube container. The foil iscomprised of an outer polyethylene layer, an adhesive layer, an aluminumfoil layer, an adhesive layer and an inner polyethylene layer. The outerpolyethylene layer will have a thickness of about 50 microns to about250 microns, the inner aluminum foil layer a thickness of about 7microns to about 50 microns, and the inner polyethylene layer athickness of about 50 microns to about 250 microns. The adhesive layersare any suitable adhesive such as ethyl acrylate copolymers, maleicanhydride modified copolymers and terpolymers, acrylic acid modifiedpolyolefins, and ethyl methyl acrylate copolymers. The adhesives willhave a thickness of about 0.25 microns to about 10 microns. Theductility of the aluminum or aluminum alloy or other metal will be about1% to 25% and preferably about 8% to 15%. This material can be stretchedabout 1% to about 25% without any breach of the aluminum foil layer.

FIG. 2 shows a typical container wall comprising an organic barrierlayer. This organic barrier layer can be any of ethylene, vinylalcoholcopolymers, polyamides, polyesters, PVDC, ClCF₃ (Aclar)®, Barex®, andnano composites and liquid crystal polymers and blends. There will be anexterior layer of polyolefin, an adhesive layer, the organic filmbarrier layer, and an inner polyethylene layer. The adhesive will be anysuitable adhesive such as any of the above described adhesives. Theouter polyolefin layer will have a thickness of about 50 microns toabout 250 microns, and preferably about 75 microns to about 200 microns.The organic barrier layer will be of a thickness of about 5 microns toabout 50 microns, and preferably about 15 microns to about 30 microns.The inner polyolefin layer will have a thickness of about 50 microns toabout 250 microns, and preferably about 75 microns to about 200 microns.These container walls can be from a laminate or can be formed byextrusion blowmolding. The container wall having this structure can bestretched about 1% to about 100%. This is greater than when a metal foilis used as the barrier layer.

It was found that a laminate structure having a 25 micron ethylene vinylalcohol barrier had equivalent to slightly improved barrier propertiesafter stretching. It is theorized that the stretching inducesorientation into the ethylene vinyl alcohol film whereby althoughthinned, it maintains or has slightly improved barrier properties withregard to flavors. This was not expected with the opinion being thatstretching the film would have a deleterious effect.

The container wall stretching by post-forming techniques will putdecorative and/or functional features onto the container wall. Thetechniques that can be used are those described in Japanese PatentPublication 56-20970 and U.S. Pat. No. 5,756,038 which are incorporatedherein by reference. Further, in a modification of the technique inJapanese Patent Publication 56-20970, the container wall can be modifiedsolely by a vacuum drawn on the mold sections or by a vacuum drawn onthe mold sections and a pressure blowing from the mandrel to provide apositive pressure in the mold. In any of these techniques the containerwall will be formed to have a stiffening shape. A third techniqueinvolves the mechanical stamping of the tube wall. This uses a mold withan expandable mandrel. The container is heated and is put into the moldand the expandable mandrel into the container. Upon actuation theexpandable mandrel then pushes the walls of the container against theinner surface of the mold, forming the surface features desired on theexterior surface of the container (see attached drawing of mandrel).

The containers that are suitable for post-forming are those that willcontain a toothpaste, a lotion, a gel product, food products,lubricants, medicants and the like. The structures that can bepost-formed onto tubes include grips and various decorations. Forinstance, a figure of a person or animal that is pictured on a tube alsocan be raised to form a more decorative tube container.

1. A method of post forming a tube container to a different shape andmaintaining the barrier properties of said tube container comprisingproviding a multilayer laminate tube having at least one barrier layerand at least one thermoplastic layer on each side of said barrier layer,said barrier layer elongatable up to about 125% of its length withoutwhereby said barrier layer maintains at least about 90% of its barrierproperties.
 2. A method as in claim 1 wherein said barrier layer is ametal layer.
 3. A method as in claim 2 wherein said metal is aluminum.4. A method as in claim 2 wherein said metal is an aluminum alloy.
 5. Amethod as in claim 2 wherein said metal is a metal film having athickness of about 7 microns to about 50 microns.
 6. A method as inclaim 2 wherein each thermoplastic layer is a polyolefin.
 7. A method asin claim 6 wherein said polyolefin is selected from the group consistingof polyethylenes and polypropylenes.
 8. A method as in claim 1 whereinsaid barrier layer is an organic barrier layer.
 9. A method as in claim8 wherein said organic barrier layer is a thermoplastic.
 10. A method asin claim 9 wherein said thermoplastic is selected from the groupconsisting of polyamides, polyesters, vinyl alcohol polymers andcopolymers, vinyl acetate polymers, vinyl chloride polymers andcopolymers, vinylidene chloride polymers and copolymers, and liquidcrystal polymers.
 11. A method as in claim 8 wherein said organicbarrier layer has a thickness of about 5 microns to about 50 microns.